How to make reliable, scalable redis on Kubernetes
This may be very late but from my understanding you don't run a service for redis itself. You're running replication of redis sentinel services so your client can connect to any of them to query master redis pod's ip address.
each pod with master has a sentinel which talks to sentinel service(s). Learning updating about the status of their master. so whenever a failover happens, sentinel updates sentinel service, sentinels select a new master and update sentinels with this info again. so whenever client queries sentinel again, it will get new master's ip address.